Integrated circuits (ICs) and other electronic apparatus often include arrangements of interconnected field effect transistor (FET) devices, also called metal-oxide-semiconductor field effect transistors (MOSFETs), or simply MOS transistors or devices. A control voltage applied to a gate electrode of the FET device controls the flow of current through a controllable conductive channel between source and drain electrodes.
Power transistor devices are designed to be tolerant of the high currents and voltages that are present in power applications such as motion control, air bag deployment, and automotive fuel injector drivers. One type of power transistor is a laterally diffused metal-oxide-semiconductor (LDMOS) transistor. Power transistor devices may have a number of features customized to prevent breakdown resulting from the high electric fields arising from such high voltages. The fabrication process flow is thus configured with a considerable number of steps directed to creating features specific to the high voltage FET devices. The steps may be highly customized to optimize the features of the high voltage devices, as well as any low voltage devices in the integrated circuit, such as complementary MOS (CMOS) logic devices.
The customization of the process flow may not be conducive to fabricating conventional designs of other semiconductor devices, such as Schottky diodes, present in the integrated circuit. Schottky diodes fabricated in CMOS process flows are typically formed with a silicide layer over an n-type or p-type crystalline silicon area. The resulting Schottky barrier junction has undesirably low breakdown voltage and high reverse leakage levels due to image force barrier lowering.
One attempt to address these deficiencies involves placing a depletion-mode LDMOS transistor device in series with the Schottky diode. Unfortunately, the LDMOS transistor device increases the footprint of the Schottky diode. The LDMOS transistor device may also involve incorporating additional procedures into the process flow, increasing the overall production cost of the integrated circuit.